Js_of_ocaml is a compiler from OCaml bytecode to Javascript. It makes OCaml programs run on Web browsers.
- It is easy to install and use as it works with an existing installation of OCaml, with no need to recompile any library.
- It comes with bindings for a large part of the browser APIs.
- According to our benchmarks, the generated programs runs typically faster than with the OCaml bytecode interpreter.
- We believe this compiler will prove much easier to maintain than a retargeted OCaml compiler, as the bytecode provides a very stable API.
- Findlib
- Lwt: version 2.3.0 at least
- Menhir
- deriving: version 0.6 at least
- optcomp
- ocp-indent: needed to support indentation in the toplevel
- cohttp: needed to build the toplevel webserver
###Opam
opam install deriving js_of_ocaml
###Manual
- edit
Makefile.confto change the default configuration - run
maketo compile - run
make installas root to install the compiler and its libraries - run
make uninstallas root to uninstall them
You can run make toplevel if you want to build a Web-based OCaml
toplevel as well. Try the toplevel
Your program must first be compiled using the OCaml bytecode compiler
ocamlc. Javascript bindings are provided by the js_of_ocaml package.
The syntax extension is provided by js_of_ocaml.syntax package.
ocamlfind ocamlc -package js_of_ocaml -syntax camlp4o -package js_of_ocaml.syntax -linkpkg -o cubes.byte cubes.ml
Then, run the js_of_ocaml compiler to produce Javascript code:
js_of_ocaml cubes.byte
Most of the OCaml standard library is supported. However,
- Weak semantic cannot be implemented using javascript.
A dummy implementation is available (use
+weak.jsoption) - Most of the Sys module is not supported.
Extra libraries distributed with Ocaml (such as Thread or Str) are not supported in general. However,
- Bigarray: bigarrays are supported using Typed Arrays
- Unix: time related functions are supported
Tail call is not optimized in general. However, mutually recursive functions are optimized:
- self recursive functions (when the tail calls are the function itself) are compiled using a loop.
- trampolines are used otherwise.
Data representation differs from the usual one. Most notably, integers are 32 bits (rather than 31 bits or 63 bits), which is their natural size in JavaScript, and floats are not boxed. As a consequence, marshalling, polymorphic comparison, and hashing functions can yield results different from usual:
- marshalling of floats is not supported (unmarshalling works);
- the polymorphic hash function will not give the same results on datastructures containing floats;
- these functions may be more prone to stack overflow.
| Filename | Description |
|---|---|
| LICENSE | license and copyright notice |
| README | this file |
| compiler/ | compiler |
| examples/ | small examples |
| lib/ | library for interfacing with Javascript APIs |
| runtime/ | runtime system |
| toplevel/ | web-based OCaml toplevel |